Key Points
- The pectoralis major muscle demonstrates two distinctively different parts—the clavicular head and the sternal head.
- The clavicular head arises from the medial clavicle and upper sternum. It is supplied by the pectoral nerve off of the lateral cord and the deltoid branch of the thoraco-acromial artery.
- The sternal head arises from the sternum, upper six ribs, and the aponeurosis of the external oblique muscle. It is supplied by the medial pectoral nerve (C8-T1) off of the medial cord.
- The most common mechanism for sustaining a pectoralis muscle injury is from weight-training or athletics.
- The patient typically presents after sudden onset of pain in the shoulder. Acutely injured patients have limited shoulder range of motion; however, the more chronic injuries typically have a full range of motion. In more chronic injuries, deformity is obvious with noticeable skin retraction and loss of anterior axillary fold.
- Imaging of soft-tissue injury in the pectoralis major can be difficult. Plain x-rays can reveal bone avulsions, or loss of pectoralis shadow. Ultrasound can demonstrate intra-muscular injury or loss of continuity of tendon. Hematoma is easily identified in acute injuries.
- Young, athletic patients will generally not tolerate the persistent weakness and cosmetic deformity that goes with pectoralis major ruptures; however, elderly or low-demand patients with pectoralis ruptures can be treated conservatively with success.
- The primary goal of surgical repair should be solid tendon apposition to bone.
- Postoperatively, the arm is placed in a sling. Patients are encouraged to perform limited activities of daily living as tolerated. Gentle ROM exercises begin immediately, avoiding early passive external rotation or abduction.
- Patients with acutely repaired tendon ruptures may return to full activity 4 to 6 months after repair. Elite weight lifters with chronically repaired tendon ruptures may not be able to return to pre-injury levels.